Editors: | F. Kongoli, M. Haumann, P. Wasserscheid, T. Welton, M. Gaune-Escard, A. Angell, A. Riisager |
Publisher: | Flogen Star OUTREACH |
Publication Year: | 2018 |
Pages: | 154 pages |
ISBN: | 978-1-987820-86-7 |
ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
Ionic liquids (IL) are drawing increasing and considerable attention in the field of catalysis as perfect, non-volatile, thermally stable solvents and media for liquid phase selective reactions [1]. We represent here examples from the catalytic chemistry, where ILs has been successfully used for improving two industrially important reactions.
Well-known commercial synthesis of terephthalic acid (TPA) is based on aerobic oxidation of p-xylene in acetic acid solution of the Co/Mn/Br catalyst, that followed by the cost and energy-consuming hydropurification of the crude TPA product from p-carboxybenzaldehyde (4-CBA) [2]. We showed that addition of ILs (dialkylimidazolium acetate and bromide) and ammonium acetate changes properties of the conventional solvent to improve solubility and accelerate oxidation of 4-CBA to TPA. Efficient combinations of the additives and appropriate reaction conditions have been selected to obtain the target product with 4-CBA content below 25 ppm [3]. Positive effect is caused by excellent solvating ability of ILs for TPA and 4-CBA. The designed catalytic systems can be applied to obtain high-quality TPA just after oxidation stage, without the hydropurification.
The next example is related to the alkylation of benzene with dodecene-1 for production of linear alkylbenzene catalyzed with binary 1-butyl-3-methylimidazolium chloride-aluminum chloride system. This catalyst showed high performance in the synthetic detergent not only from neat dodecene-1, but from the feedstock containing a mixture of C10-C13 alkanes and C10-C13 alkenes. The best results have been obtained when the mole fraction of [BMIM]Cl ionic liquid is around 40%. Furthermore, the optimal reaction conditions, such as benzene/alkene ratio (1.6-3) and temperature (30-40°C), have been found. In this case, a very high 98-99% yield of detergent is achieved [4].